The invention relates to an airbag system for motor vehicles, and more particularly to an airbag having a gas generator which retracts in a cavity of the motor vehicle away from an occupant during a collision.
Gas bag systems, with which, in the event of an accident of the motor vehicle, a cushion automatically inflates in front of the occupant from activation of a gas generator, are known for both the driver's seat and the passenger's seat.
To ensure reliable protection of the occupant in the event of an impact of the motor vehicle, the cushion must be inflated in a very short time. In practice, the inflation takes place within a few milliseconds. This ensures that, in the event of an impact, the cushion is already inflated before the occupant is thrown in the direction of the cushion. The assumption is made that the occupant is sitting back in a normal position in the seat such that the occupant does not come into contact with the cushion during its inflation.
However, if the occupant has leaned forward during impact of the motor vehicle, his head may be positioned within the space provided for the inflation of the gas bag. Since the gas bag inflates rapidly, it is possible that parts of the covering cap may strike the occupant, whereby injuries may occur.
It is known from German Patent No. DE 42 27 559 A1 to inflate the gas bag with a comparatively slower expansion speed in the direction of the occupant (hereinafter the "axial direction") and with a comparatively greater expansion speed in the lateral direction. However, this arrangement has the disadvantage that the gas bag may not yet be fully inflated in the critical axial direction when the occupant is thrown forward upon impact, such that the gas bag does not provide adequate cushioning.
It is further known from U.S. Pat. No. 5,383,682 to mount the airbag system on a plastically deformable support. This support is deformable by means of a force which is applied thereto by the occupant after inflation of the airbag. With this arrangement as well, it is not possible to prevent the occupant from being hit by the deploying gas bag and being injured thereby.
From U.S. Pat. No. 4,200,309, a steering wheel is also known, whereby a box-type element is present inside the rim of the steering wheel, which element is deformable under the impact of an occupant's head. This is intended to reduce the risk of injury. The disadvantage of this steering wheel consists in that it can be effective only with slight decelerations of the vehicle, but that with rapid decelerations, such as occur in the event of a crash, injury is only insignificantly reduced. Further, an airbag for protection of the occupant in the event of a crash is not provided with this steering wheel.